Comparison of human growth hormone releasing factor (hGRF) (1-29) -NH2 formulated by Serono Labs, with same peptide formulated at University of Virginia, will determine bioavailability of this natural sequence peptide by monitoring its efficacy in stimulating GH release and by measurement of GRF levels when given subcutaneously. This study is to determine the effects on GH release, the duration of activity and potency compared with a single dose of hGRF(1-40). Ten normal men will be studied on 7 separate days.